Probable Maximum Flood (PMF) is mostly applied for the designs of large-scale hydraulic structures and it is estimated by computing the runoff hydrograph where Probable Maximum Precipitation (PMP) is inserted as design rainfall. The existing PMP is estimated by transferring the heavy rainfall from all watersheds of korea to the design watershed, however, in this study, PMP was analyzed by selecting only rainfall events occurred in the design watershed. And then, Catchment-scale Soil Erosion Model (CSEM) was used to estimate the PMF and sediment-runoff yield according to the watershed-based estimated PMP. Although the PMF estimated in this study was lower than the existing estimated PMF in the Yongdam-dam basin, it was estimated to be higher than the 200-year frequency design flood discharge. In addition, sediment-runoff yield was estimated with a 0.05 cm of the maximum erosion and a 0.06 cm of the maximum deposition, and a total sediment-runoff yield of 168,391 tons according to 24-hour PMP duration.
Spatial Fragmentation Analysis of Upland Fields Using Farm Manager Registration Information
As food consumption pattern changes (reduced rice consumption and increased consumption of fresh vegetables), managing upland fields became a greater priority. However, the agricultural infrastructure projects have been focused on rice farming, and the infrastructure level to support dry fields cultivation is insufficient. The purpose of this study was to spatial distribution analysis of these dry fields with farm manager registration information. Using FRAGSTATS, we analyzed landscape indices (TA/CA, NP, PD, LSI, LPI, PLADJ, COHESION, CONNECT, AI) of farmlands in which farmers in 13 regions (Si or Gun) cultivated dry-field crops. As results of this analysis, the total area of the fields in Naju-si, Hampyeong-gun and Suncheon-si were found to be wider, but the average area of a patch in Youngam-gun, Hampyeong-gun and Jangseong-gun were wider than other regions. On average, each farmer had farmlands containing of 1.7~2.4 patches and cultivated crops in fields of 0.2~0.5 ha. Farmlands of Hampyeong-gun, Youngam-gun, Naju-si showed high values in adjacency indices, however the farmlands of Suncheon and Gwangyang showed fragmented distribution with low values in adjacency indices. These results of fragmentation analysis of farmlands could be used when we establish the plan of an agricultural infrastructure project or select places for a collaborative agricultural management business promotion project.
Analysis of Disk Filter Head Losses due to the Shapes of Disk Grooves in Drip Irrigation System
정승연 Jung Seung-yeon , 최원 Choi Won , 최진용 Choi Jin-yong , 김마가 Kim Maga , 이윤희 Lee Yoonhee
Drip irrigation system is a low energy cost method which can efficiently save and supply water by dropping water slowly on the crop’s root zone during crop growth. In the drip irrigation system, disk filters take an important role to physically remove impurity (inorganic and suspended organic) particles present in agricultural water which can cause emitter clogging. For the purpose, both top-and-bottom surfaces of the disk are grooved in micron size flowing from outside to inside. However, many congested flow paths in disk filter media incur higher head loss of inflow water resulting in relatively decreasing velocities depending on operation time than sand and mesh filters. Therefore, it is important to optimize the structure of disk filter in micro irrigation system. The head loss of disk filter media takes also charge of more than 60 % of total head loss in whole disk filter. This study is to find the appropriate cross-sectional shape of the disk groove to minimize the head loss by executing the experiment. The experiment used three disk filters that have similar filter body but have a half-elliptic and two kinds of triangular cross sections. The experimental results showed that the disk filter with half-elliptic cross sections of disk grooves have less head loss than the disk filter with regular triangular one.
A Study to Define USLE P Factor from Field Survey in the Four Major Watersheds
유나영 Yu Nayoung , 신민환 Shin Minhwan , 서지연 Seo Jiyeon , 박윤식 Park Youn Shik , 김종건 Kim Jonggun
Universal soil loss equation (USLE) had been employed to estimate potential soil loss since it was developed from the statewide data measured and collected in the United States. The equation had an origin in average annual soil loss estimation though, it was modified or improved to provide better opportunities of soil loss estimation outside the United States. The equation has five factors, most studies modifying them to adapt regional status were focused on rainfall erosivity factor and cover management factor. While the conservation practice factor (USLE P factor) is to represent distinct features in agricultural fields, it is challenging to find studies regarding the factor improvements. Moreover, the factor is typically defined using slopes. The factor defining approach was suggested in the study, the approach is a step-by-step method allowing USLE P factor definition with given condition. The minimum condition is slope and field location to provide an opportunity for using in any GIS software and to reflect regionally distinct features. If watershed location, slope, crop type, and mulching type on furrows are given, detailed definition of the factors are possible. The approach was developed from field survey in South-Korea, it is expected to be used for potential soil loss using USLE in South-Korea.
Estimation of the Probable Maximum Water Thermal Energy in Korean Dams based on the Water-Energy Nexus Concept
Demand for essential resources including water, energy and food is rapidly increasing due to climate change, population growth and urbanization. To solve this problem, the concept of water-energy-food nexus has been introduced, and many countries have been trying to acquire the Nexus technology that can maximize the efficiency by analyzing the interconnection between resources. In this regard, this study attempted to estimate the probable maximum water thermal energy in the dam based on the water-energy nexus concept. The estimation of the probable maximum water thermal energy was implemented to monthly water storage of the largest dams in the four major river systems. As a result of analyzing the estimated monthly water thermal energy from 2000 to 2016, Soyang River dam has the largest probable maximum water thermal energy, and Sumjin River dam has the smallest. However, the probable maximum water thermal energy was small in common between March and April, between September and October due to the small temperature difference between the ambient air and the dam water. Also, according to the characteristics of the dam, Daecheong dam and Soyang River dam were beneficial for supplying water thermal energy for heating, and Sumjin River dam and Andong dam were advantageous for supplying water thermal energy for cooling. Our findings can be useful to realize the water-energy-food nexus by increasing the utilization and value of water resources as well as expanding the roles and functions of dams as a starting point to use dam water thermal energy.
Evaluation of Drought Monitoring Using Satellite Precipitation for Un-gaged Basins
장상민 Jang Sangmin , 윤선권 Yoon Sunkwon , 이성규 Lee Seongkyu , 이태화 Lee Taehwa , 박경원 Park Kyungwon
This study analyzed the applications of near real-time drought monitoring using satellite rainfall for the Korean Peninsula and un-gaged basins. We used AWS data of Yongdam-Dam, Hoengseong-Dam in Korea area, the meteorological station of Nakhon Rachasima, Pak chong for test-bed to evaluate the validation and the opportunity for un-gaged basins. In addition, we calculated EDI (Effective doought index) using the stations and co-located PERSIANN-CDR, TRMM (Tropical Rainfall Measurement Mission) TMPA (The TRMM Multisatellite Precipitation Analysis), GPM IMERG (the integrated Multi-satellitE Retrievals for GPM) rainfall data and compared the EDI-based station data with satellite data for applications of drought monitoring. The results showed that the correlation coefficient and the determination coefficient were 0.830 and 0.914 in Yongdam-dam, and 0.689 and 0.835 in Hoengseng-Dam respectively. Also, the correlation coefficient were 0.830, 0.914 from TRMM TMPA datasets and compasion with 0.660, 0.660 based on PERSIANN-CDR and TRMM data in nakhon and pakchong station. Our results were confirmed possibility of near real-time drought monitoring using EDI with daily satellite rainfall for un-gaged basins.
A Study on the Effect of Residents’ Participation on Community Consciousness and Tourism Development Attitudes - Focused on DMZ Peace Village Site -
양민호 Yang Min Ho , 고진영 Koh Jin Young , 김명일 Kim Myung Il , 김기성 Kim Ki Sung
This study aims to analyzes the Relationship Between Community Consciousness and Residents’ Participation in Tourism Development. Starting in 2004, the Rural Tourism Development Project, which has been promoted in Korea, is taking a bottom-up approach that values the participation of residents. And Resident’s Participation is also an important criterion for selecting business sites. As the farming community becomes more modern, the community consciousness is declining. But Community consciousness is an important factor for the sustainable maintenance of rural villages. And if community members share a sense of homogeneity, they can identify problems that communities have, and they can solve them with responsibility. Community consciousness can be called the basic infrastructure of residents’ participation. Rural tourism feature different characteristics from other tourist areas in that the residential space of local residents is the destination of the tours. As a result, the influence on tourism development is directly affected, so the attitude of local residents is an important success factor unlike other tourism developments. The study analyzed the community consciousness and participation in Tourism Development, which is a significant success factor in rural areas. The survey which included 200 residents of the DMZ Peace Village Site, was concluded that the member’s perception and ttachment among Community Consciousness affected the Residents’ Participation, and that Economic Influence among tourist development attitudes affected the Residents’ Participation. It based on the results in rural tourism development for the residents’ participation should be considered with a plan to enhance the economic life satisfaction and promote the economic impact on the area.
Estimation of THI Index to Evaluate Thermal Stress of Animal-occupied Zone in a Broiler House Using BES Method
하태환 Ha Taehwan , 권경석 Kwon Kyeong-seok , 홍세운 Hong Se-woon , 최희철 Choi Hee-chul , 이준엽 Lee Jun-yeob , 이동현 Lee Dong-hyun , 우샘이 Woo Saemee , 양가영 Yang Ka-young , 김락우 Kim Rack-woo , 여욱현 Yeo Uk-hyeon , 이상연 Lee Sangyeon , 이인복 Lee In-bok
Thermal stress of livestock has been issued due to recent climate change trends and this causes reproductive disorders, decreased feed consumption, immunosuppression, and increased mortality of animals. Concept of THI has been widely used to quantitatively evaluate the degree of thermal stress for animals, however use of this concept is restricted for animals living in the enclosed facilities such as mechanically ventilated broiler houses. In this study, time-based internal energy flow and variation trends of temperature and humidity were analyzed based on BES technique. Local weather data, insulation characteristics of building materials, heat and moisture generation rate from broilers according to age, algorithm of ventilation operation were adopted for boundary condition of the model to accurately compute THI values inside the mechanically ventilated broiler house. From the BES computation, excess frequency of THI threshold in Jeju city was highest on the assumption that air conditioning equipments were not installed. When general raising density (39 kg m -2) was adopted, total 2,191 hours were exceeded. Excess hours of THI threshold were strongly related to the cumulative air temperature (R 2 =0.87).
Structural Behavior of Sandwich Type GFRP Arch and Field Applicability
황대원 Hwang Dae-won , 김광우 Kim Kwang-woo , 김용성 Kim Yong-seong , 연규석 Yeon Kyu-seok
This study investigated the structural behavior and field applicability of sandwich type GFRP arches with polymer mortar in core. As a result, in case of crack loading and failure loading, total strains at crown were the highest; the fracture strain at crown was 0.01690, which is 4.2 times greater than the fracture strain (0.004) of cement concrete. The 3 % deflection load was 17.42 kN, the flexural strength was 163.98×10 -3 GPa, and the flexural elastic modulus was 11.884 GPa. From load-deflection relationship up to 3.5 % deflection, 3D analysis results and experimental values were observed to be almost identical. It was considered reasonable to set a deflection rate limit to be 3 % for structural safety purpose. The standard external flexural strength of semicircular arch used in this study was approximately 2.64 times higher than that of hume pipe (2 type standard) and tripled composite pipe. The external pressure strength at fracture was approximately 1.57 times higher than that of hume pipe. It was confirmed that the implementing semicircular arch had mechanically more advantage than the circular pipe. Optimum member thickness was 8~53 mm according to arch radius of 450~1,800 mm and cover depth of 2~10 m. It was found that the larger strength could be obtained even if the thickness of member was smaller than that of concrete structure. In field application study, figures and equations were derived for obtaining applicable cover depth and optimum member thickness according to loading conditions. These would be useful data for design and manufacture of sandwich type semicircular arch.
Probabilistic Analysis of Liquefaction Cyclic Stress Ratio Considering Soil Variability
The objective of this study is to evaluate the liquefaction cyclic shear stress ratio considering the soil uncertainty. In this study, the probabilistic ground response analysis and the cyclic shear stress ratio analysis for the liquefaction potential evaluation are performed considering the soil variability. The statistical properties of input ground parameters were analyzed to investigate the parameters affecting the seismic response analysis. The Probabilistic analysis was carried out by Monte Carlo Simulation method. The ground response analysis was performed considering the soil variability and the probability distribution characteristics of the ground acceleration. The probability distribution of the peak ground acceleration by seismic characteristics was presented. The differences of liquefaction shear stress ratio results according to soil variability were compared and analyzed. The maximum acceleration of the ground by the deterministic method was analyzed to be overestimation of the ground amplification phenomenon. Also, the shear stress ratio was overestimated.
Experiment Study on Field Applicability of Siphon as a Intake Facility of Agricultural Reservoir for Disaster Prevention
양영진 Yang Young Jin , 이태호 Lee Tae Ho , 오수훈 Oh Sue Hoon
Most of the intake facilities of small agricultural reservoirs are conduits and they are regarded as serious defects due to the structural weakness that penetrates the body of the dam, and countermeasures are needed. This study suggests the application method of siphon type water intake facility by hydraulic model test and physical scale model test of siphon type water intake facility which has high safety and easy maintenance. Experimental results show that sufficient flow rate can be secured for the purpose of intaking water according to the differential head between the reservoir and the discharge part, and the flow rate can be controlled by the valve. The negative pressure was -31.5 kPa, and vibration and noise did not occur during the operation of the siphon. The maximum flow velocity in the discharge outlet was 1.11 m/s which meets the criterion for irrigation canals. Therefore, scour risk would be very low. As a result of the inflow distribution experiment, even if the inflow part is separated by only about 0.8 m, the flow velocity is remarkably decreased, so that the clogging by debris would not appear. When the pump was operated only once for the first time and the inside of the siphon was filled with water, continuous operation was possible by only valve operation. The results of this study are expected to be used for the design guidelines of the water intake facilities and improve safety and maintenance convenience of agricultural reservoirs.
Change Analysis of the Rural Development Policy based on Budget Distribution (1997~2015)
김대식 Kim Dae-sik , 권용대 Won Yong-dae , 배승종 Ae Seung-jong , 김수진 Im Soo-jin , 김성필 Im Seong-pil
The purpose of this study is to analyze the changes of rural development policies in the last 20 years by analyzing the budget distribution by policy objectives and support factors. 1997, 2000, 2005, 2010 and 2015 Guidelines of Agricultural, Food and Rural Development Project were analyzed to identify the budget distribution. The objectives of rural development policy were classified into 5 fields and 27 detailed factors such as production environment, distribution environment, technology and human resources, living environment, income support. The support factors of rural development policy were classified into 3 fields and 17 detailed factors. The budget of rural development policy has greatly increased from 952,297 million won in 1997 to 4,869,174 million won in 2010 and 3,905,340 million won in 2015. In budget distribution by policy objectives, the policy was mainly focused on management funding in 1997, 2000 and in the 2000s, it was confirmed that investment in the improvement of the living environment was rapidly taking place. In budget distribution by policy support factors, it was found that living environment and welfare environment support factor in rural area occupied the largest portion and welfare, tourism, and living environment has been rapidly increasing since 2005.
Impact of Water Management Techniques on Agricultural Reservoir Water Supply
류정훈 Ryu Jeong Hoon , 송정헌 Song Jung Hun , 강석만 Kang Seok Man , 장중석 Jang Jung Seok , 강문성 Kang Moon Seong
Along with climate change, it is reported that the extreme climate events such as severe drought could cause difficulties of agricultural water supply. To minimize such damages, it is necessary to secure the agricultural water resources by using or saving the amount of irrigation water efficiently. The objectives of this study were to develop paddy water management scenarios and to evaluate their effectiveness on water saving. Three water management scenarios (a) deep irrigation with ponding depth of 20~80 mm (control, CT), (b) no/intermittent irrigation until paddy cracks (water management A, WM-A), and (c) intermittent irrigation with ponding depth under 20 mm (water management B, WM-B) were developed. Water saving effects were analyzed using monitored data from experimental paddy fields, and agricultural water supply was analyzed on a reservoir-scale using MASA model. The observed irrigation amounts were reduced by 21 % and 17 % for WM-A and WM-B compared to CT, respectively, and mainly occurred by the increase of effective rainfall. The simulation results showed that water management scenarios could reduce irrigation by 21~51 % and total inflow by 10~24 % compared to CT. The long-term simulated water level change of agricultural reservoir resulted in the decrease of dead level occurrence for WM-A and WM-B. The study results showed that WT-A and WT-B have more benefit than CT in the aspect of agricultural reservoir water supply.
